The invention discloses an inwards-expanding type indexing fixture. The inwards-expanding type indexing fixture comprises a rotating shaft and a fixed disc, the rotating shaft penetrates through the fixed disc, an axial blind hole is formed in the end of the right side of the fixed disc, and a compression spring and a steel ball are arranged inside the blind hole. An indexing disc is arranged at the position, located on the right side of the fixed disc, of the rotating shaft in a sleeving mode, a set of clamping grooves are formed in the end of the left side of the indexing disc, one part of the steel ball is located inside the blind hole, and the other part of the steel ball is located inside the corresponding clamping groove. The position, located on the right side of the indexing disc, of the rotating shaft is sleeved with a positioning tube fixedly connected with the indexing disc, the positioning tube is sequentially sleeved with an elastic sleeve and a compression sleeve from left to right, the compression sleeve is connected with the positioning tube through threads and sleeved with a compression tube, and the compression tube is connected with the compression sleeve in a threaded mode. A locking nut is further arranged on the position, located on the right side of the positioning tube, of the rotating shaft. The technical defects that in the prior art, when equally divided grooves are machined in the outer wall of a tubular workpiece, operation is troublesome, efficiency is low, and errors are large are overcome, and the inwards-expanding type indexing fixture is easy to operate and high in efficiency and has small errors.